Traditional vehicles powered by an internal-combustion engine typically heat a passenger cabin of the vehicle using waste heat generated by the engine. Coolant heated by the engine is circulated to a heater core disposed within a heating ventilation and air conditioning (HVAC) unit. The HVAC unit includes a blower that circulates an airstream through the heater core and into the passenger cabin to provide heat.
To improve fuel economy and diminish environmental impact, electric and hybrid electric vehicles have been developed to improve fuel economy and reduce pollution. These vehicles may generate none or insufficient engine waste heat to meet cabin-heating requirements. Consequently, other sources of heat are needed to sufficiently heat the cabin.